Some local dog walkers alerted Steve to a regular Barn Owl local to Sawbridgeworth, and we've managed to see it a couple of times. We decided on Sunday to see if it had survived the Snow, and were rewarded with not one but two Barn Owls hunting together.
We noticed one was paler than the other, and duly hit Google today. I came across this and this
The abstracts are all written in that weird form of English that scientists use when presenting their work. I recognise and understand the words, it all appears to be grammatically correct, but when I stand back and look at it I haven't a clue what it means.
It states that male Barn Owls are paler than females, so we may have been watching a pair (this makes sense as they hunted together without any rancour or aggression).
It also states that darker Barn Owls are healthier than pale ones, and that darker birds pass on their extra darkness to offspring of either sex.
The second reference contains this:
"In northern Europe, male and female T. a. guttata are reddish-brown and heavily spotted, and in southern Europe male and female T. a. alba are white, but only females display many spots. Here, I discuss the relative importance of direct selection, genetic correlation and the post-ice age invasion of Europe by T. alba, in generating sex-specific cline variation in plumage spottiness and non-sex-specific cline variation in plumage coloration".
and elsewhere there's reference to 25+ races of Barn Owl across the globe.
So, the Barn Owl contains features that make it a messenger of evolution, and in particular contains information of the spread of birds after the ice ages, but unpicking that information seems to be beyond science at the moment.